Understanding White Balance or
Color Temperature

The Color of Light
Everyone has taken at least one photograph that has been
way off in color. You get it back from whoever processed
it, or if it is from a digital camera you load it into
your computer, and your immediate response is ďwhat the
heck happened?Ē. Everything has a weird color cast to
it, either orange, green or blue.

Light has a definite color to it depending on the light
source and itís surrounding conditions. As humans we
donít recognize the changes in the color of light, for
the most part, because our brains adjust for it.

The color of light is measured in degreeís Kelvin. This
is referred to as color temperature. The lower the color
temperature, the redder the light is. The higher the
temperature, the bluer the light is.

Letís look at sunlight. Throughout the day the color
temperature of sunlight changes because of itís angle
and the surrounding atmospheric conditions. Early in the
morning and late in the evening sunlight gets a warm
golden glow to it. Photographers refer to this time as
the golden hour. During the middle of the day however
the light is very blue, around 5500-6500 degrees kelvin.
This is the color temperature of most flash units. In
the shade, the color temperature of light is around 7500
degrees kelvin.

Artificial light on the other hand is a whole different
ball game. Letís take a look at incandescent light
bulbs. These are every day light bulbs. On average the
color temperature of a light bulb is around 3200 degrees
kelvin. They have a strong orange color cast. This is
evident if you are outside, late in the evening and look
at the windows of a lit up house. The light in the
windows will have an orange cast that is very easy to
see. It used to be that florescent lights were at about
4000 degrees kelvin. This color temperature would record
with a green cast on daylight balanced film. These days
florescent lights can be purchased at different color
temperatures.

The Recording Media and Corrective Options
Because of the way light can shift color a white object
may not record as white on different recording media. As
far as this article is concerned, there are two types of
light recording media. One is photographic film and the
other is a digital camera. Letís look at film first.

Photographic film records the light that is reflected
off an object. If the object is grey, how do we get the
image on film to be grey, if we donít know what color
the light is that is hitting the grey object and
reflecting onto the film? Film manufacturers have
basically solved this problem by calibrating the film to
a certain color balance or color temperature. You have
two choices, daylight (5500 degrees kelvin) or tungsten
(3200 degrees kelvin). So if you are shooting film
outdoors, you would choose daylight balanced film. If
you are shooting indoors, you would choose tungsten
balanced film. Any deviation in color temperature from
these two standards would have to be corrected with a
color correction filter.

A digital camera works pretty much the same as film. The
recording device in the camera has to be calibrated to
the color of the light in order to get a neutral image.
Neutral meaning no color cast. A white will record as
white. Different digital cameras use different methods
of letting you choose the color balance. Most digital
cameras will have an auto white balance function. In
most situations this works fairly well. However there
are occasions when the camera can be fooled. This is why
a lot of digital cameras also give you a way of setting
the white balance manually. Either through a list of
choices like daylight, shade or overcast, or a list of
color temperatures such as 3200, 5500 and 6500. Some
digital cameraís take it a step further and let you
choose a custom white balance by having you photograph
something white and use it as a reference for white
balance.

Getting Creative
By using the white balance in your digital camera you
can ďset it wrongĒ to create different moods of light in
your images. As an example, lets say you are
photographing a field covered in snow on a sunny day but
you want the image to reflect the fact that it is only
10 degrees outside. If you were to set your digital
cameraís white balance at anything lower then 5500
degrees kelvin the resulting image would have a blue
cast to it making your image Ďfeelí cold. Experiment a
little with it. Donít just play around with aperture and
shutter speed, play with the white balance too.